Molecular aspects of the regulation of granulocyte-macrophage production from colony-forming cells form the basis of this project. Hemopoietic regulators are produced in conditioned media and purified using column chromatography and electrophoresis. The molecular properties of GM-CSF and CFS's specific for other cell lineages are studied in detail. Separation of progenitor cells and immature myeloid cells is achieved using the fluorescence-activated cell sorter for quantitative analysis of lectin binding. Molecular changes induced by GM-CSF in progenitor cells, mature neutrophils and a myelomonocytic leukemia WEHI-3B are being analyzed using two-dimensional electrophoresis.